The present invention relates to a universal interface for coupling to a host computer port type of a host computer system.
Personal computers (xe2x80x9cPCsxe2x80x9d) use a variety of techniques for providing input and output via peripheral devices. In the past, the PCs have included a serial port, usually an RS232 or RS485, and a parallel port in several ISA expansion slots included on the motherboard. Connecting the PCs to anything more complicated than a mouse, modem or printer usually required the lid to be taken off the PC, dip switches to be set, and software configured. A SCSI (small computer systems interface) device permitted access to external storage devices, but required a large cable connector with the need to manually set ID numbers and have a terminal.
The universal serial bus (xe2x80x9cUSBxe2x80x9d) is specified to be a new industry standard extension to the PC architecture with a focus on computer telephony interface, consumer and productivity applications. The USB architecture provides for ease of use for peripheral expansion, transfer rates up to twelve megabits per second, protocol flexibility for mixed modes, isochronous data transfers, and asynchronous messaging and has begun to replace earlier generational serial interfaces such as RS485. USB is a cable bus supporting data transfer between the host PC and a range of simultaneously operable peripherals. One host controller can support up to 127 physical devices using a tiered star topology. The hub is at the center of each star with each wire segment creating a point-to-point connection of up to five meters. The five meter limitation may be between a host and hub or a hub function or a hub connected to another hub or function.
As the point of sale industry begins the transition to USB architecture instead of legacy RS232 or RS485 or other custom interfaces, a problem exists because manufacturers need to produce two sets of similar peripheral devicesxe2x80x94one device for use with a PC with USB architecture, and a second, similar device for use with a host computer with RS485 architecture. Therefore, equipment suppliers are faced with manufacturing two sets of similar products that will be sold and co-exist in the field for some period of time after the introduction of USB.
Thus, a need exists in the art where one device or peripheral can be sold so that it may be operably connected to a host computer having either a USB or RS485 or other serial bus capabilities. This unresolved problem and deficiency is clearly felt in the art and is solved by the invention in the manner described below.
The foregoing need is addressed by the present invention which provides an universal interface, electrically connected to a peripheral device, comprising a first or a second cable type for coupling the universal interface to a host computer, circuitry for sensing a voltage presented at the first or second port type, and circuitry for establishing a first or second data communications link between the host computer and the peripheral device via the universal interface in response to the voltage sensed.
Additionally, the present invention provides a data processing system comprising a host computer with either a first or second communications bus, a universal interface coupled to a first or second port type of the host computer, circuitry for determining a first or second voltage at the respective port, and circuitry for establishing the proper data communications path between the host computer, universal interface and peripheral device connected thereto.
Finally, the present invention provides a methodology for selectively enabling one of two interface logic circuits when a universal interface is coupled to a host computer.
The foregoing has outlined rather broadly the features and technical advantages of the present invention in order that the detailed description of the invention that follows may be better understood. Additional features and advantages of the invention will be described hereinafter which form the subject of the claims of the invention.